Rotating impeller type mixing devices are in wide use in industry. For example, there are many types of mixing devices that generally utilize a mixing vessel to hold the fluid and/or other mixing material, which is to be mixed or agitated. The vessels can be of any suitable shape, including for example cylindrical, oval, square, etc. A motor driven impeller shaft extends into the vessel and has paddle type impellers radially extending therefrom so that when the shaft is rotated the impellers agitate and/or mix the material inside the vessel.
In some applications, such as particularly sanitary applications including, for example, pharmaceutical or food operations, it is generally desirable for the mixing device to be cleaned into a highly sterile condition before the material is added, and to be sealed during the mixing operation so that the material does not become contaminated. This concern is particularly heightened in the case of biological mixing reactions in the pharmaceutical and biotechnology industries.
A frequently used type of known mixing device has a vessel and some form of closure seal attachment via which the mixing shaft projects into the vessel. In order to clean this type of device thoroughly enough for some applications, it is necessary to dismantle the seal and undergo a time consuming and laborious cleaning process. It is common for seals to be cleaned in-situ by SIP (steam in place) and/or CIP (clean in place, flush with acid & caustic solutions). Further, this cleaning process generally needs to be carried out at the site location where the mixing device is located, requiring additional steam or chemical cleaning equipment to be present at that site. Further, at the actual mixing site it may be difficult for the operators to know if they have satisfactorily performed the cleaning.
Accordingly, there is a need in the art for a mixing apparatus and method that can provide a highly clean or sterile internal environment at a mixing site, while also being convenient and practical to use.